In recent years, innovative energy-saving illumination products and technologies have been advancing, particularly LED illumination products which are of high luminous efficacy and long lifespan, luminous efficacy increased 5-10 times and lifespan extended 30-50 times compared to incandescent lamp. Therefore, the energy-saving reformation of various conventional illuminations has been recognized by businesses and users, more particularly EMC (Energy Management Contract) mode has attracted more and more attention.
The theoretical lifespan (Note: Product lifespan refers to the service time till the luminous flux of the product decreases to 70%.) of innovative energy-saving illumination products as LED is very long, however, since there is no feasible accelerated ageing test methodology to validate its lifespan, the luminous flux maintenance factor at 6000 hours or even longer with conventional ageing is commonly adopted at present to judge the lifespan. Since the technology of innovative energy-saving illumination as LED is developing very fast, its technology may already be out-of-date normally when a product lifespan has just been or not yet been sufficiently validated, causing both waste of time and money for LED manufacturers. As for users, unless a failure happens to the product in a short time, the actual operating time of the product can not be accurately measured, thus it's hard to validate the lifespan of the illumination product and this might offend their legal rights. For instance, the nominal lifespan of a product is 25000 hours, but if the product fails at 20000 hours, it's hard for the user to provide evidence or defend his/her legal rights.
Therefore, lifespan assessment and validation of innovative energy-saving illumination products as LED is a severe issue besetting manufacturers and users.